sundance-communications.com/forum Forums Other TDM Phone Systems 1A2 and Comkey Telephones & Systems ITT BLF Phone

Looking at Matt's last post we strayed a little into a new thread on Busy Lamp Fields.

Anyone remember an ITT 10 Button Phone with a built in BLF (where the second keystrip would go)?

Arthur and I had discussed BLFs and his experience with the Phone factory was to use -24vDC lamps. In my experience (Interconnect) I remembered 10vAC lamps.

As I recall, we would put two diodes in each set and feed A1 ground through a spare hookswitch contact to the BLF. The BLF itself sat on Battery.

Anyone else have experience with this?

And does anyone remember the part number of the ITT BLF set, which if my (poor) memory serves me well, was not duplicated by anyone else - WE, NT, SC or AE.

Sam

Sam, I don't remember the nominclature but do remember the sets and the 10v set up....and the seven button built-in speaker phones.

ITT was a good source for the 1A2 special sets.

Sam, you are correct in remembering that only ITT made these integrated sets. I think that they used 24 volt lamps though. I remember a kit of parts (basically two diodes with spade-tips on the ends) that were formed into a "wye". These were installed in each station in the switch hook wiring for the "A" lead, which is 24VDC.

All BLF's sat on B battery since they relied upon station switch hook control of the A1 (ground) lead. The diodes just kept other off-hook stations from back-feeding the BLFs.

Allen Tel (Graybar) and Stromberg-Carlson made an external BLF and their's worked on 24 volts also. Same deal with the diode requirement on a per-station basis. The 50 pair line cord for those things weighed more than the console itself, so they were hard to keep on the desk.

Comkey 718, 1434 and 2152 sets came with this functionality built in, so if a DSS console was added, there was no field modification of the station sets required. Those systems definitely used 24 volt lamps.

Ed -

The first thing I would do when Installing a 1A2 system (after running a cold water ground) was to common all the grounds on the Power Supply - A Bat, B Bat, 10V, 18V and Ringing. (That's how I was always taught).

I that case it wouldn't matter what "A" was.

Was this not a common practice?

I remember the 24v lamps - I think they were 52A's.

Sam

Ken -

You're right about those speakerphones 7 line and 17 line built-ins. They were nice units.

Sam

an addendum to my previous post - 52A lamps were (as I recall) 24v (we used them in battery-backed up key systems), but the ones in the ITT BLF set were "grain-of-wheat" with two little needle connectors on the bottom.

Were they 24volt? I can't remember.

Sam